1. Field of the Invention
The present invention is related to horn type loudspeakers employing high and low frequency drivers using a common horn to direct sound to the listener. This invention is also directed to an acoustic horn apparatus that can provide an improved full spectrum sound.
2. Description of the Prior Art
U.S. Pat. No. 5,526,456 identifies a number of goals for an acoustic horn or loudspeaker. These goals include use of as little power as possible and to provide a compact horn without unduly sacrificing sound reproduction characteristics. Sound should be directed to the listener with as little blocking and interference as possible. Horn loudspeakers should also be concentrated so that the sound is directed to the listener. In a loudspeaker or horn apparatus using multiple drivers, the sound waves emanating from the mouth of the speaker should also be in phase.
Prior art horn in horn loudspeakers have incorporated a high frequency horn within a low frequency horn to integrate their coverage. In some prior art devices the smaller high frequency horn creates an acoustic shadow and low frequency sound waves can be blocked. If the high frequency drivers are placed in front of the low frequency drivers in a prior art horn in horn apparatus, the sound leaving the speaker will be out of phase.
U.S. Pat. No. 5,526,456 employs a pair of high frequency drivers mounted to the side of the horn centerline and connected to the horn throat by a single coupling passage. Two low frequency drivers are located on opposite sides and are each also connected to the throat by coupling passages. A common virtual or apparent source is created for both high frequency and low frequency so that all sound appears to emanate from the same point. Another version includes only a single high frequency driver and a single low frequency driver. U.S. Pat. No. 6,343,134 discloses a number of other prior art loudspeaker systems, including some with multiple drivers in a single horn.